U.S. patent application Ser. No. 181,974, filed Aug. 28, 1981 and now abandoned and Ser. No. 295,400, filed Aug. 21, 1981, both of which are now owned by Flexwatt Corporation, the assignee of the present application, disclose a flexible sheet heater in which a semi-conductor pattern including a pair of longitudinally-extending stripes is printed on a substrate. A thin copper electrode is placed on each strip and is there held in place by a cover sheet that is attached, at opposite sides of the electrode, to closely-adjacent portions of the underlying substrate.
The present invention is directed to improvements in such sheet heaters.